Autism and Genes Connection

by National Institute of Health

What are genes?

Genes are pieces of DNA, material that contains all the information needed to "build" a person. Genes are hereditary, meaning parents pass genes on to their children.

Most genetic material is found in the nucleus of a cell, a storage area that keeps these materials together in one place. The nucleus stores genetic materials in packages called chromosomes. Most people have 46 chromosomes in most of their cells: 23 from their mother and 23 from their father. Each chromosome is made up of genes.

Genes contain the information your body uses to make proteins, the body's building blocks. Proteins make up the structure of your organs and tissues; they are also needed for the body's chemical functions and pathways. Each protein performs a specific job in the body's different types of cells, and the information for making at least one protein is contained in a single gene.

The pattern or sequence of your genes is like a blueprint that tells your body how to build its different parts. For example, your genes control how tall you are, what color your eyes and hair are, and other features of your body and mind. Changes, or mutations in the blueprint can change how the body or mind grows/develops.

What is autism?

Autism is a complex neurobiological disorder of development that lasts throughout a person's life. It is sometimes called a developmental disability because it usually starts before age three, in the developmental period, and because it causes delays or problems in many different skills that arise from infancy to adulthood.

The main signs and symptoms of autism involve1 language, social behavior, and behaviors concerning objects and routines:

Communication - both verbal (spoken) and non-verbal (unspoken, such as pointing, eye contact, or smiling)

Social interactions - such as sharing emotions, understanding how others think and feel (sometimes called empathy), and holding a conversation, as well as the amount of time a person spends interacting with others

Routines or repetitive behaviors - often called stereotyped behaviors, such as repeating words or actions over and over, obsessively following routines or schedules, playing with toys or objects in repetitive and sometimes inappropriate ways, or having very specific and inflexible ways of arranging items

People with autism might have problems talking with you, or they might not want to look you in the eye when you talk to them. They may have to line up their pencils before they can pay attention, or they may say the same sentence again and again to calm themselves down. They may flap their arms to tell you they are happy, or they might hurt themselves to tell you they are not. Some people with autism never learn how to talk.

These behaviors not only make life difficult for people who have autism, but also take a toll on their families, their health care providers, their teachers, and anyone who comes in contact with them.

Because different people with autism can have very different features or symptoms, health care providers think of autism as a "spectrum" disorder - a group of disorders with a range of similar features. Based on their specific strengths and weaknesses, people with autism spectrum disorders (ASDs) may have mild symptoms or more serious symptoms, but they all have an ASD. This fact sheet uses the terms "ASD" and "autism" to mean the same thing.

What causes autism?

Scientists don't know exactly what causes autism. Much evidence supports the idea that genetic factors - that is, genes, their function, and their interactions - are one of the main underlying causes of ASDs. But, researchers aren't looking for just one gene. Current evidence suggests that as many as 12 or more genes on different chromosomes may be involved in autism to different degrees.

Some genes may place a person at greater risk for autism, called susceptibility. Other genes may cause specific symptoms or determine how severe those symptoms are. Or, genes with mutations might add to the symptoms of autism because the genes or gene products aren't working properly.

Research has also shown that environmental factors, such as viruses, may also play a role in autism.

While some researchers are examining genes and environmental factors, other researchers are looking at possible neurological, infectious, metabolic, and immunologic factors that may be involved in autism.

Because the disorder is so complex, and because no two people with autism are exactly alike, autism is probably the result of many causes.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.